We've got a couple of DeckLink 8K Pro cards that we are using in 4-channel half-duplex mode to capture up to 4 1080i/60 streams (upgraded from DeckLink Quads). Using the same code we had been using for the Quads, we are able to capture one stream seemingly without issues. Two streams usually work, but after some time (30 minutes to a few hours) we get intermittent or complete audio dropouts on one or both of them, and have to reboot the machine to get things back to normal (restarting our program doesn't change things). With four streams this starts to happen very quickly (within a minute or two).

Specifically, the symptom is that we continue to receive audio callbacks, but the buffer received only contains zeros. We've been able to reproduce this on two different cards.

I tried initializing all streams from the same process/thread vs. different processes; this didn't seem to make any difference.

Using one subdevice as input while other subdevices are acting as outputs doesn't seem to trigger the issue.

Once the problem is triggered, even the SDK sample capture program is not able to capture audio from the card until after a reboot - though I have not yet tried to trigger the bug using just the sample program.

This is on Linux, with Desktop Video 11.4. We have tried several kernel versions (4.9, 4.19, 5.2) and have seen the same issues on all of them. The system is a Xeon E5-2630v3, 32GB RAM, Supermicro X10DRL-i motherboard.